No abstract available.
Radiotherapy*

Radiotherapy

The quasi-conformation therapy was performed to get a homogeneous dose distributions for irregeular shaped tumor lesion by using the arc moving beam and beam modifying filer which was made by cerrobend alloy (p=9.4g/cc) metal. In our dose calcuation programme, it was fundmentally based on Clarkson's method to calcuate the irregular multi-step block field in rotation therapy. In this study, the expected relative depth doses under multipartial attenuator agree well with measured data at same plane. The results of comparison the dose computation with that of TLD measurement are very closed within +/-5% uncertainties in the irradiation to phantom with quasi-comformation method. And it has shown that irregular typed multi-step filter can be applied to quasi-conformation therapy in high energy radiation plannings.
Alloys ; Radiotherapy*

No abstract available.
Melanoma* ; Radiotherapy*

No abstract available.
Germinoma* ; Radiotherapy*

PURPOSE: To analyze the long-term stability of Farmer-type cylindrical ionization chambers by calibration factor provided from the KFDA (Korea Food Drug Administration) MATERIALS AND METHODS: The cylindrical ionization chambers used in this study were the PTW 30001 (30006), 30013, 30002, 30004, 23333, the Capintec PR06C, the NE 2571, the Exradin A12 and the Wellhofer FC65G (IC70). We were analyzed that the N(k) and N(D,W) calibration factor for the cylindrical chambers and compared between the measured N(D,W) and calculated N(D,W) calibration factor. RESULTS: We have observed that the long-term stability of the PTW 30013 (30006), the Wellhofer FC65G (IC70) and the NE 2571 has varied within 0.2%. The measured N(D,W) calibration factor was about 1.0% higher than the calculated N(D,W) that determined by the N(k) calibration factor. CONCLUSION: The study has evaluated that the long-term stability of the cylindrical chambers through analysis for the Nk and N(D,W) calibration factor. It has contributed to the improvement of clinical electron dosimetry in radiotherapy centers.
Calibration ; Radiotherapy

The study involved 51 patients with primary brain tumors and 8 patients with brain metastasis from acute leukemia. Age of patients ranged from 5 to 70 years. Drugs for anti-cerebral edema were administered 48 - 72 hours before radiotherapy. For patients with high-volume primary brain tumors, synacthen 1 mL x1 ampoule daily was used and dexamethasone 16-20 mg daily was administered during radiotherapy. For patients with acute leukemia, dexamethasone 8 - 16 mg was used daily. Results: It is possible to prevent from acute cerebral complications if the conventional dose division of radiotherapy is performed appropriately with use of anti-cerebral edema drugs around radiotherapy. The closed monitoring must be given for cases in which chemotherapy, especially methotrexate, was used with radiotherapy
Brain ; Radiotherapy

No abstract available.
Hysterectomy* ; Radiotherapy

The purpose of study is to investigate whether glass rod detector (GRD) would be suitable for dosimeter of radiotherapy units. A GRD is used for the measurement of the output factors and x-axis beam profiles from Gamma Knife. The output factors measured with GRD from the 14, 8 and 4 mm collimators relative to the 18 mm collimator are 0.980+/-0.013, 0.949+/-0.013 and 0.872+/-0.012, respectively. The output factors obtained with a GRD are within 1.0% in good agreement with the values recommended by the manufacture. The full width at half maximum (FWHM) of x-axis beam profiles measured with GRD are 5.9 mm at a 4 mm collimator.
Glass* ; Radiotherapy

This study was designed to evaluate radiosurgery technique using multiple noncoplanar arc therapy with intensity modulated fine MLC shaped photon beam. The stereotactic radiosurgery was performed with 6-MV X-ray beams from a Clinac 21EX LINAC (Varian, Palo Alto, CA, USA) with a MLC-120, which features a full 40 x 40 cm field and is the first MLC for general use that offers 0.5 cm resolution for high precision treatment of small and irregular fields. We used a single isocenter and five gantry-couch combinations with a set of intensity modulated arc therapy. We investigated dosimetric characteristics of 2 cm sized spherical target volume with film (X-OMAT V2 film, Kodak Inc, Rochester NY, USA) dosimetry within 25 x 25 cm acrylic phantom. A simulated single isocentric treatment using inversely planned 3D radiotherapy planning system demonstrated the ability to conform the dose distribution to an spherical target volume. The 80% dose level was adequate to encompass the target volume in frontal, sagittal, and transverse planes, and the region between the 40% and 80% isodose lines was 4.0~4.5 mm and comparable to the dose distribution of the Boston Arcs. We expect that our radiosurgery technique could be a treatment option for irregular-shaped large intracranial target.
Radiosurgery* ; Radiotherapy ; Radiotherapy, Intensity-Modulated*